NAHR AL-BARED PALESTINIAN REFUGEE CAMP, Lebanon
— As battles between the Lebanese Army and Islamic militants from Fatah al-Islam entered a third day, dozens of residents of this embattled Palestinian camp seized a chance Tuesday to flee.

They waved white sheets from cars as snipers still fired at them during a brief cease-fire. "The situation is very miserable," screamed Mouein Safadi as he reached an Army post. "There are many, many people dead under the rubble. We have no water, no food, no electricity."

Ahmad Afif, driving a battered red Renault filled with his family, said the militants "are not Palestinians. They are Syrians, Iraqis, Afghanis. What do they want from us?"

The violence that began Sunday – as the Army grew determined to root out an estimated 100 militants with suspected ties to Al Qaeda – is the latest unrest within the country's Palestinian refugee camps, which have a history of spawning both secular and Islamist militants.

And as Palestinians in some of Lebanon's 11 other camps protested the government offensive in Nahr al-Bared, the unrest here threatens to spread to an estimated 210,000 refugees who live in slumlike camps where only hopelessness and poverty seem plentiful. On Tuesday, as fierce fighting continued between the militants and the Army, angry Palestinians in other camps set car tires ablaze.

Outside the camp in Tripoli, the country's second-largest city, a militant blew himself up when confronted by security forces. In all, at least 29 soldiers and 20 militants have been killed in the three-day battle.

If the violence, already the worst internal strife since the 1975-90 civil war, does continue, it will indeed threaten an already vulnerable government that faces a growing domestic challenge from an opposition movement led by Syrian- and Iranian-backed Hizbullah. The Lebanese government has accused Syria of backing Fatah al-Islam as well, a charge that the Syrians deny.

Most of Lebanon's refugee camps have existed since 1948, when Israel was established and tens of thousands of Palestinians fled to neighboring countries.

The camps were set up generally on the outskirts of towns and cities and initially consisted of little more than canvas tents. Over the years and as their population numbers swelled, the refugees built simple homes from cinder blocks and cement, turning the encampments into small villages that often lacked proper sanitation, electricity, and water. While more than 200,000 Palestinians are believed to live in the camps, the United Nations reports that 424,650 Palestinians live throughout the country.

During the 1960s and 1970s, the camps were the breeding ground for Palestinian militants in Lebanon and Jordan determined to win back their homes in Israel. The Palestinian factions grew increasingly powerful, and their cross-border attacks created problems for their host governments. In 1970, the Jordanian Army clashed with Palestinian militants and thousands were ejected from the country, joining their comrades in Lebanon.

The growing influence of the mainly Sunni Palestinian armed factions upset Lebanon's delicate sectarian balance and was a factor that led to the outbreak of civil war in 1975. Israel invaded Lebanon twice in the next seven years to drive the Palestinian militants out of Lebanon.

Since the end of the civil war in 1990, the Palestinians have been confined to their 12 established refugee camps, which are ringed by Lebanese troops and whose entrances are tightly controlled.

The Lebanese state has no jurisdiction over the camps, a result of an agreement dating back to 1969 that Lebanon still honors. The Lebanese government refuses to accept the possibility of the refugees being permanently housed in Lebanon, fearing that it will aggravate sectarian sensitivities.

Palestinians are forbidden from all but the most menial labor, and the Lebanese state bans the refugees from expanding the area of the allotted camps. It even refuses to allow construction material inside.

Widespread poverty has helped foster the emergence of radical Islamist groups in some of the camps, particularly Ain al-Hilweh on the outskirts of the southern port city of Sidon where 50,000 people are packed into less than a square mile.

One of the older militant Islamist factions is Esbat al-Ansar, which emerged in the early 1990s and is based in Ain al-Hilweh. Listed by Washington as an international terrorist group, Esbat al-Ansar carried out a number of attacks and robberies around Sidon in the late 1990s, including the gunning down of four Lebanese judges in a courtroom in 1999.

Esbat al-Ansar and a splinter faction called Jund ash-Sham are thought to have organizational links with Fatah al-Islam and include fighters who have fought in Iraq.

A year ago, the Lebanese government began attempting to improve conditions in the camps, setting up a liaison channel with Palestinian representatives to install proper sewage systems, electricity, and water networks and to construct new homes.

According to Khalil Makkawi, a former Lebanese diplomat and the government's representative in the talks with the Palestinians, about $23 million has been pledged by donor nations in the past year to upgrade conditions in Lebanon's camps.

"We have made considerable progress in improving human conditions," he says.

Infrastructure work has begun in one of Beirut's camps and will soon begin in Ain al-Hilweh, he says.

Yet, analysts say, while improvements will help, resolving the plight of the camps is ultimately a political matter and hinges on progress in the moribund Israeli-Palestinian peace process.

Raising fears of spreading violence, an explosion went off in a shopping area in a Sunni Muslim sector of Beirut late Monday, wrecking parked cars and injuring seven people – a day after a bomb blast in a Christian part of the capital killed one woman. A Fatah al-Islam spokesman denied that the group was behind either bomb blast.

At the Nahr al-Bared camp, a convoy of six UN trucks carrying water, food, and medical supplies, took advantage of the temporary cease-fire Tuesday to enter the camp in the afternoon.

A Lebanese military intelligence officer said that Fatah al-Islam had threatened to bombard nearby Tripoli and the adjacent town of Minieh with rockets if the Army offensive continued.

The militants are believed to have a large stockpile of weaponry, and sources close to the group said that the fighters are in secure positions and prepared for a long battle. One sobbing woman who had just left the camp said that some 300 residents came out of hiding during the cease-fire and were demonstrating against Fatah al-Islam.

"They were calling on them to leave," she says, "but they opened fire on them."